This invention involves heat insulation for the roofs of industrial buildings about the purlins and roof panels supported by the purlins. More particularly, this invention provides a heat block in the hot zone about the purlins of an industrial building.
Heat insulation material placed in walls, ceilings, roofs, and floors of building structures typically comprise fibrous blanket insulation, such as elongated blankets formed of fiberglass or other fibrous materials. The principle of the insulation blanket is to form dead air spaces between the fibers that provide insulation against convection and conduction heat transfer. The blanket insulation can be formed in small xe2x80x9cclumpsxe2x80x9d of fibrous material and blown into spaces such as into the attics of residential homes and other building structures. The fibrous insulation also can be made into elongated blankets formed in a specific width and depth that is suitable for placement between parallel joists, studs, rafters, and other parallel support structures that are uniformly spaced apart. The elongated blanket, such as a fiberglass blanket, is cut to the desired length at the job site for placement between the parallel structures. Also, a sheet of facing material usually is applied to one broad surface of the insulation blanket, with the facing material having overhanging edges or xe2x80x9ctabsxe2x80x9d extending beyond the sides of the blanket that can be applied by the installer to adjacent studs, joists, purlins, etc. of the building structure to hold the blanket in place.
Fiberglass is one of the most desirable materials for forming blanket insulation because it holds its shape and traps a substantial amount of air between its fibers to form the dead air spaces. However, the fiberglass alone does not provide adequate heat insulation against radiant heat transfer.
With regard to industrial buildings of the type having exposed rafters and purlins that support the outside roof sheets, blanket insulation can be applied with the lengths of the blanket extending parallel to the purlins and with the blankets positioned in the spaces between the purlins. It is desirable to have the blankets fill all of the available space between the purlins, but the upper laterally extending flange of the typical Z-shaped purlin or of the typical I-shaped purlin tends to compress or crush portions of the blanket adjacent the purlins, so that some of the air is forced out of the blanket and the heat insulation capacity of the blanket is reduced. This is referred to herein as a xe2x80x9chot zone.xe2x80x9d
Another problem with the prior art blanket insulation of industrial building is the radiant heat transmitted through the roof structure. Fiberglass insulation does not form an effective radiant heat reflector so as to insulate against radiant heat transmission through the roof structure. U.S. Pat. No. 5,918,436 discloses the concept of installing radiant heat reflective sheets between adjacent purlins in a roof structure of an industrial building, so as to provide the desired radiant heat insulation to the structure. Also, in the recent past, an additional sheet of reflective material has been applied to one of the broad surfaces of the fibrous insulation blanket for radiant heat reflection. The reflective material, such as aluminum foil, functions as a barrier to radiant heat transfer. However, the use of the reflective material does not adequately solve the problem of insulating the hot zone about the purlins.
Another problem with the prior art insulation for industrial buildings is that the roof panels that form the outside surface of the roof usually makes direct contact with the upper laterally extending flange of the purlin, or is insulated therefrom with inadequate insulation, providing heat transfer from the roof panels to the purlin, and then to the inside of the building.
This invention concerns the above noted problems.
Briefly described, the present invention comprises an improved heat insulation assembly for placement in, and for becoming a part of, an industrial building of the type that includes a plurality of equally spaced parallel purlins supporting roof panels, with these materials being made of steel, aluminum or other metals. The heat insulation assembly can insulate the building from conduction, convection and radiation heat transfer through the roof structure of the building.
While this invention disclosure is specifically directed toward the heat insulation of a roof structure, it will be understood that the same principles of the invention can be applied to walls, floors, ceilings, and virtually any type of enclosure in which the temperature, humidity and other aspects of the environment are controlled inside the building but the exterior temperature and humidity remain uncontrolled and typically the temperature moves to levels higher than and lower than the interior temperature.
In the disclosed embodiments of the invention, a feature of the invention is an insulation heat block that is positioned between the purlins and the roof panels, with the heat block extending laterally beyond the purlins into the hot zone adjacent the purlins. The heat blocks each include a central body that rests upon the purlin and side portions that extend laterally beyond the central body for extending out into the space adjacent the purlins, so as to fill the hot zone adjacent the purlins with insulation of known value. This configuration of the side portions moves any crushed blanket insulation away from the purlins or fills any vacant space adjacent the purlins, and assures that known insulation value will be provided by the heat block directly adjacent the purlins and between the purlins and the roof panels.
Another feature of this invention is the use of insulation blankets that are positioned between adjacent purlins. The blankets include opposed side edges having conductive heat insulation formed therein for placement between the upper flange of the purlins and the roof panels for the purpose of insulating against conductive heat transfer through the roof. The insulated edges of the blankets are manufactured with and become a part of the insulation blanket before the blanket reaches the roof structure, so that the blanket with its insulated edges can be installed in a single operation. The insulated edges of the blankets can be formed of strips of air cell blanket, strips of fiberglass or of other fibrous materials, or other suitable conduction heat insulation material.
The insulation blankets extending between adjacent purlins can be formed of, for example, fiberglass blanket, air cell blanket, heat reflective sheets, or a combination thereof.
Another feature of this invention is the use of radiant heat reflective sheets that extend between adjacent ones of the purlins for the purpose of reflecting radiant heat and for insulating the roof structure from heat transfer due to radiation. The radiant heat reflective sheets perform best when the reflective surfaces are maintained in a clean state and are positioned away from adjacent objects so as to provide a clear or xe2x80x9cdead airxe2x80x9d space immediately adjacent the reflective surfaces, thereby maintaining their capacity to reflect radiant heat.